As a method for cooling a reduced-iron agglomerate discharged from a reduced-iron production equipment, a method has heretofore been put into practical use wherein a reduced-iron agglomerate is immersed and cooled in a water bath, thereafter taken out from the water bath with a conveyer, discharged directly to an earth floor and stored in stacks, and then, according to circumstances, conveyed and charged into an electric arc furnace.
However, the reduced-iron agglomerate produced by this immersing and cooling method has a high water content and, when it is charged directly into molten metal, there is the danger of a water vapor explosion. Therefore, it has been used only for charging into an electric arc furnace. Moreover, the reduced-iron agglomerate has the problems of pulverization and reoxidation.
Japanese Patent No. 3145834 discloses a method for producing reduced-iron briquettes wherein reduced iron produced by a direct reduction ironmaking method is formed into briquettes by a briquette machine and the reduced-iron briquettes are cooled slowly, at a cooling rate of 150 to 250° C./min., with a water spray.
However, this method is a method wherein high-temperature reduced-iron briquettes are cooled slowly with a water spray in order to suppress cracking of the reduced-iron briquettes and not a method wherein a reduced-iron agglomerate discharged from a reduced-iron production equipment, such as a rotary hearth furnace, is cooled. Moreover, this method does not take an appropriate water content of the reduced-iron agglomerate into consideration.
Further, Japanese Patent No. 3009661 discloses a method wherein high-temperature reduced-iron briquettes having been heated and reduced are cooled with water so that an average cooling rate may be in the range from 1,500 to 500° C./min. during the time when the surface temperature decreases from 650° C. to 150° C.
However, this method is one that is related to the cooling of reduced-iron pellets that are different in size and features from an agglomerate such as briquettes as intended in the present invention. Therefore, this method cannot be applied as it is.
In addition, though the temperature of a reduced-iron agglomerate discharged from a rotary hearth furnace is about 1,000° C., the patent describes neither a cooling method and a cooling rate in the temperature above 650° C. nor a concrete cooling means even in the temperature below 650° C., and further pays no attention at all to the water content of agglomerate.